Abstract: Bosonic many-body systems are prominent candidates for a quantum advantage
demonstration, with the most popular approaches being either a quantum
simulation beyond the reach of current classical computers, or a demonstration
of boson sampling. It is a crucial open problem to understand how resilient
such quantum advantage demonstrations are to imperfections such as boson loss
and particle distinguishability. We partially solve this problem by showing
that imperfect multi-boson interference can be efficiently approximated as
ideal interference of groups of smaller number of bosons, where the other
particles interfere classically. Crucially, the number of bosons undergoing
interference in our approxmation only depends on the level of imperfections,
but is independent of the actual number of particles. This allows us to
construct a simple but stringent benchmark for comparing many-body bosonic
technological platforms.